Valveless rotary piston expansion engine

ABSTRACT

A rotary piston expander engine of the trochoidal type is described wherein the four phases of an expander cycle, i.e., intake, expansion, exhaust and recompression, are performed in a working chamber without using any external valving. A compressible working fluid at high temperature and pressure is injected in the working chamber during the intake phase by proper alignment of a passage through the output shaft and eccentric, a slot in a bushing serving as a rotor-eccentric bearing, and one of the slots in the rotor flanks. A face seal is used to interface the rotating shaft with a source of the working fluid. Exhaust phase is also accomplished without external valving by properly aligning a rotor side seal passage over ports in the end plates of the working chamber.

United States Patent [191 Dugan et al.

[ Nov. 11, 1975 154] VALVELESS ROTARY PISTON EXPANSION ENGINE [75]Inventors: Martin F. Dugan, Portsmouth;

Daniel A. Bowlus, Middleton, both of R.l.

221 Filed: Feb. 6, 1974 21 Appl. No.: 439,802

[56] References Cited UNITED STATES PATENTS 3,255,737 6/l966 Nallingen418/61 A 3,426,525 2/1969 3,549,110 12/1970 3,744,940 7/1973 3,825,3757/1974 Deone 418/186 FOREIGN PATENTS OR APPLICATIONS United Kingdom418/187 Primary E.\'anzinerCarlt0n R. Croyle Assistant E \'mninerL. J.Casaregola Attorney, Agent, or Firm-Richard S. Sciascia; Arthur A.McGill; Prithvi C. Lall [57] ABSTRACT A rotary piston expander engine ofthe trochoidal type is described wherein the four phases of an expandercycle, i.e., intake, expansion, exhaust and recompression, are performedin a working chamber without using any external valving. A compressibleworking fluid at high temperature and pressure is injected in theworking chamber during the intake phase by proper alignment of a passagethrough the output shaft and eccentric, a slot in a bushing serving as arotor-eccentric bearing, and one of the slots in the rotor flanks. Aface seal is used to interface the rotating shaft with a source of theworking fluid. Exhaust phase is also accomplished without externalvalving by properly aligning a rotor side seal passage over ports in theend plates of the working chamber.

US. Patent Nov. 11, 1975 Sheet 1 of2 3,918,859

FiG.l

Sheet 2 of 2 3,918,859

US. Patent Nov. 11, 1975 FIG.4

FIG.3

FIG. 6

VALVELESS ROTARY PISTON EXPANSION ENGINE STATEMENT OF GOVERNMENTINTEREST The invention described herein may be manufactured and used byor for the Government of the United States of America for governmentalpurposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION This invention relates to rotary pistonengines and more specifically to a valveless rotary piston positivedisplacement expansion engine of trochoidal type.

The rotary piston engine originally patented by F. Wankel for internalcombustion application serves as the basic rotary piston engine. Oneinteresting feature of the Wankel rotary piston engine is that theoutput shaft rotates at three times the speed of the rotor with respectto the housing. This characteristic allows a point on theshaft-eccentric to align in succession with SUMMARY OF THE INVENTION Theobjects and advantages of the present invention are accomplished byutilizing a rotary piston positive displacement expander engine whereinthe four phases of an expander cycle, i.e., intake, expansion, exhaustand recompression, are performed without any external valving in aworking chamber which moves with the rotary piston inside a two-lobetrochoidal outer hous- I ing. A compressible working fluid at hightemperature and pressure from an external source is introduced duringthe intake'phase by proper alignment of a drilled passage through theoutput shaft and eccentric, a slot in a bushing serving as therotor-eccentric bearing and a slotin one of the rotor flanks, thuseliminating external valving during the intake phase of the cycle.Exhaust phase of the expander cycle is also accomplished by timing rotorside seal passage over the ports in the end plates of the workingchamber.

An object of this invention is to have a rotary piston positivedisplacement expander engine wherein intake phase of an expander cycleof the engine is performed by introducing a working fluid into a workingchamber without any external valving.

Another object is to have a rotary piston positive displacement expanderengine wherein exhaust phase of the expander cycle after the expansionphase is accomplished without any external valving.

Still another object is to have a rotary piston engine wherein theworking chamber, where expander cycles -are performed, moves with therotary piston inside a two-lobe trochoidal outer housing.

Still another object is to have a rotary piston engine wherein thelength of a rotor slot controls the duration of the intake phase.

Still another object is to have a rotary piston engine wherein arotating shaft-eccentric is interfaced with an external source ofworking fluid by means of a face seal.

Other objects, advantages and novel features of the invention willbecome apparent from the following detailed description of the inventionwhen considered in conjunction with the accompanying drawings wherein:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view ofthe working chamber of the rotary piston positive displacement expanderengine including a showing of intake passage and exhaust passage;

FIG. 2 shows the relative positions of the shafteccentric, the bushing,and the rotor;

FIG. 3 is a diagrammatic representation of the working chamber, theposition of the rotor and the shafteccentric at the start of an intakephase (top portion) of the expander cycle;

FIG. 4 is a diagrammatic representation of the position of the workingchamber, the rotor, and the shafteccentric at the cut-off portion of theexpander cycle;

FIG. 5 is a diagrammic representation of the position of the workingchamber, the rotor, and the shafteccentric during the intake phase(bottom portion) of the expander cycle;

FIG. 6 is a diagrammatic representation of the position of the workingchamber during the exhaust phase of the expander cycle; and

FIG. 7 shows the shape of the exhaust ports of the rotary piston engine.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring to the drawings whereinlike reference characters designate like parts throughout the severalfigures, and more particularly to FIG'. 1 thereof, a rotary pistonpositive displacement expander engine is shown. The expander enginecomprises a working chamber 10 in housing 11 which is enclosed on bothends by means of end plates 12 and 14 and the use of through bolts suchas through bolt 16. Attached to the end plate 12 is a tubing 18 providedwith a flange 20 which is fastened to end plate 12 by means of bolts 22and 24. Shaft 26 has its end 28 passing through end plate 14 and has itsend 30 passing through end plate houses rotor 34. Rotor 34 is providedwith a bushing 36 I having a slot or opening 38 in it. Bushing 36 ismade of a solid lubricant such as graphite, which serves to provide cutoff or closure of the eccentric passage. End40 of tubing 18 has apassage or opening 42 for an intake connection to a stationary externalsource of a compressible working fluid at high temperature and pressure.Passage or opening 42 in tubing 18 extends throughout its length. A faceseal 44 is housed near end 40 of the tubing 18 and is spring-loaded bymeans of spring 46 as shown in FIG. 1. Passage or opening 42 is incommunication with passage or opening 48 of the face seal which in turnis in communication with passage or opening 50 in shaft 26. Passage 50extends to nearly the center part of the working chamber and iscontinued through eccentric portion 32 of the shaft 26 as passage oropening 52. Passage or opening 52 is alignable with slot 38 of thebushing 36 and also alignable with a slot or opening such as opening 54of rotor 34. The relative positions of shaft-eccentric 26, bushing 36,and rotor 34 are shown in FIG. 2. Bushing 36 is permanently attached torotor 34.

When passages 42, 48, 50, 52, 38 and 54 are aligned and are incommunication, the working fluid is admitted to the working chambertherethrough during the intake phase of the expander cycle (topportion). The position of shaft 26 and its eccentric piece 32, rotor 34and bushing 36 is shown in FIG. 3 wherein passages 42, 52, 38 and 54 arein communication with one another. As can be seen from FIG. 3, flank 56of rotor 34 is in the upper portion of the working chamber 10 enclosinga minimum portion of the space in the working chamber 10. It should benoted that the rotating shafteccentric unit 26 is interfaced with thestationary fluid source by face seal 44. The motion of rotor 34 is sotimed that the working fluid is introduced in the working chamber 10 atminimum volume positions as shown in FIGS. 3 and 5. FIG. 5 representsthat part of the intake cycle where flank 58 is in such a position as tooffer minimum volume for the intake of working fluid. As can be seenfrom FIGS. 3, 4 and 5, the relative mo tion between the rotor 34 andshaft-eccentric 26 allows the working fluid to be introduced every timeone of the rotor slots 54, 62 and 64 in rotor flanks 56, 58 and 60respectively comes to a position to offer minimum volume to the workingfluid. FIG. 4 represents that part of the expander cycle wherein passage50 is out of communication with rotor slot 54, and thus representscutoff phase of the expander cycle. FIG. 6 shows the sealing grid of theworking chamber wherein side seals on rotor 34 are used to uncover partsin the end plates 12 and 14 of the engine to allow for exhaustion of theexpanded working fluid. Arrow 69 shows the direction of rotation ofrotor 34 during an expander cycle of the engine. The triangularly-shapedports 66 and 68 are so located and sized to provide the desired exhaustphase. As an example, line 70 might be determined by the rotor side sealposition at maximum expansion. Line 72 represents the rotor side sealposition at desired exhaust closure and line 74 is any line that willnot inter- .fere with the engine functions and it determines the.maximum exhaust area.

P tween the rotor and eccentric and allows passage of working fluid to acorresponding rotor slot. The intake process continues until theeccentric passage has moved the entire length of one of the rotor slotsafter which it is stopped by the eccentric-rotor bushing. Furtherrotation causes the eccentric to come into a position to fill anotherrotor flank which has reached a position wherein the working chamber hadminimum volume. Side seals on the rotor are used to uncover ports in theend plates for exhaustion of the expanded working fluid. The length ofthe rotor slots controls the duration of the intake phase, the locationof the eccentric passage in relation to the rotor slots at minimumvolume of the working chamber determines the start of the intake phase,and the bushing serves to provide cut-off or closure of the eccentricpassage or opening. The passage of the side seal of the rotor controlsthe opening and closing of the side port.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. As an example, a solidlubricant other than graphite may be used for the bushing serving as therotor-eccentric bearing. Alternatively, some other arrangements such asa rolling element bearing or a hydrodynamic bearing may also be used.Furthermore, an arrangement other than a face seal may be used tointerface the rotating shaft-eccentric with the external stationarysource of a working fluid. It is therefore understood that within thescope of the appended claims the invention may be practiced otherwisethan as specifically described,

We claim:

1. A valveless rotary piston engine of the external combustion and opencycle type having a rotor with multiple flanks and side seals andmounted on a shafteccentric for rotational motion within a housingenclosed by a first end-plate and a second end-plate and defining aworking chamber of variable-volume during the rotation of said rotor byintroduction of a gaseous working fluid at relatively high pressure andtemperature in said working chamber, an improved means for controllingthe introduction of said working fluid in said working chamber from anexternal source thereof which comprises:

a first passage through said shaft eccentric for receiving said workingfluid from said external source;

a second passage through said rotor and a bushing attached to saidrotor, said bushing having a first plurality of slots and said bushingserving as a rotorshaft eccentric bearing, said second passage being inand out of alignment with first passage during the rotation of saidrotor;

a second plurality of slots in said rotor, each of said multiple flanksof said rotor having at least one slot of said second plurality ofslots, each slot of said first plurality of slots in said bushing beingaligned with a corresponding slot of said second plurality of slots insaid rotor; and

a pair of exhaust ports in said second end-plate, each one of said pairof exhaust ports being covered and uncovered in succession during therotation of said rotor.

2. The improved means of claim 1 for controlling the introduction ofsaid working fluid into said working chamber wherein said first passage,said second passage and one of said plurality of slots in said rotor arein alignment during an intake phase of an expander cycle of saidvalveless engine to allow said working fluid in said working chamber.

3. The improved means of claim 1 for controlling the introduction ofsaid working fluid into said working chamber wherein said workingchamber is in communication with one of said pair of exhaust portsduring an exhaust phase of the expander cycle of said valveless Engineto expel working fluid. from said working cham- 4. The improved means ofclaim 1 for controlling the introduction of said working fluid into saidworking chamber wherein said first passage in said shafteccentric isinterfaced with said source of said working fluid by means of a faceseal.

5. The improved means of claim 1 for controlling the introduction ofsaid working fluid into said working chamber wherein said bushing ismade of a solid lubricant.

6. The improved means of claim 5 for controlling the introduction ofsaid working fluid into said working chamber wherein said solidlubricant for making said bushing is graphite.

1. A valveless rotary piston engine of the external combustion and opencycle type having a rotor with multiple flanks and side seals andmounted on a shaft-eccentric for rotational motion within a housingenclosed by a first end-plate and a second endplate and defining aworking chamber of variable volume during the rotation of said rotor byintroduction of a gaseous working fluid at relatively high pressure andtemperature in said working chamber, an improved means for controllingthe introduction of said working fluid in said working chamber from anexternal source thereof which comprises: a first passage through saidshaft eccentric for receiving said working fluid from said externalsource; a second passage through said rotor and a bushing attached tosaid rotor, said bushing having a first plurality of slots and saidbushing serving as a rotor-shaft eccentric bearing, said second passagebeing in and out of alignment with first passage during the rotation ofsaid rotor; a second plurality of slots in said rotor, each of saidmultiple flanks of said rotor having at least one slot of said secondplurality of slots, each slot of said first plurality of slots in saidbushing being aligned with a corresponding slot of said second pluralityof slots in said rotor; and a pair of exhaust ports in said secondend-plate, each one of said pair of exhaust ports being covered anduncovered in succession during the rotation of said rotor.
 2. Theimproved means of claim 1 for controlling the introduction of saidworking fluid into said working chamber wherein said first passage, saidsecond passage and one of said plurality of slots in said rotor are inalignment during an intake phase of an expander cycle of said valvelessengine to allow said working fluid in said working chamber.
 3. Theimproved means of claim 1 for controlling the introduction of saidworking fluid into said working chamber wherein said working chamber isin communication with one of said pair of exhaust ports during anexhaust phase of the expander cycle of said valveless engine to expelworking fluid from said working chamber.
 4. The improved means of claim1 for controlling the introduction of said working fluid into saidworking chamber wherein said first passage in said shaft-eccentric isinterfaced with said source of said working fluid by means of a faceseal.
 5. The improved means of claim 1 for controlling the introductionof said working fluid into said working chamber wherein said bushing ismade of a solid lubricant.
 6. The improved means of claim 5 forcontrolling the introduction of said working fluid into said workingchamber wherein said solid lubricant for making said bushing isgraphite.